1. Field of the Invention
This invention relates to a support bar for adjustably mounted accessories and particularly to an extruded support bar for electric lights such as theatrical lamps and adapted to receive electric wiring therein. Also the support bar may serve as a conduit for wires such as fiber optic wiring without departing from the spirit of the invention.
2. Description of the Prior Art
Prior to the present invention theatrical lights for motion picture sound stages and theatrical stages consisted of an elongated hollow tube that was preferably horizontally mounted with a series of holes bored diametrically through the tube. When it was desired to mount a theatrical light or lamp that included a mounting bracket a bolt passed through the diametric bores and a nut held the lamp in place.
The wires running to the lamp passed within the tube and exited a bore near the mounting holes.
The disadvantage of this arrangement has been that there was no true adjustability of the lamp on the bar. If the lamp has to be moved the bolt and nut must be removed and inserted in another of a series of mounting holes.
In other words the positioning of the lamps along the bar were at the control of the locations of the mounting holes. If there were no mounting holes at the location on the bar where the lamp should be mounted the exact desired position could not be achieved.
Further, with the light bar being drilled with a series of diametric mounting holes the structural integrity of the bar was weakened. With a series of lamps suspended from the bar and such weakness occurs the bar could break.
Also with the prior art lighting bars the electrical wires passing through the bar and not being separated or in separate cable compartments or electrical raceways just add to the chances of shorting and other electrical problems.
In addition, in camera mounting bars for vehicles in the motion picture business again diametric holes are provided, but true adjustability of the cameras or lamps on the exterior of the vehicle for interior vehicle shots is limited.
Further, with prior art camera mounting bars the bar can also achieve structural weaknesses causing collapse of the same. This is particularly true with the weight of conventional motion picture cameras.